How Matt Duffy became one of MLB’s best rookies

Over the past half decade, the San Francisco Giants have found ways of getting meaningful contributions out of players who were thought to be past their prime or not highly-regarded. This year, the Giants have nurtured the offensive development of three infielders who didn’t show much power before the major leagues, turning what might otherwise have been an average lineup into one of the best offenses in baseball.

Those three infielders are Matt Duffy, Brandon Crawford, and Joe Panik. Together they form three quarters of one of the most productive offensive infields in the game, and it’s fair to say not many people predicted that statement being made about the Giants before the start of the season. The stories behind Crawford and Panik’s breakouts have already been chronicled: through a few swing changes and pulling more fly balls, both Giants middle infielders have increased their power production by leaps and bounds this season. However, it’s not terribly surprising these two are putting it together, as one (Panik) was a highly-regarded prospect, and the other (Crawford) was a very good college player.

The same cannot be said of Matt Duffy. An 18th-round pick in the 2012 draft out of Long Beach State, Duffy tallied a total of 501 college at-bats, but never hitting a homer. Over parts of three years in the minors between 2012-14, Duffy hit 13 homers in 1,087 plate appearances: that’s a minor-league home run rate of one every 84 plate appearances. Houston’s Jose Altuve hit a home run, on average, every 77 plate appearances between the 2013 and 2014 seasons, so Duffy homered in the minors at a rate just below what Jose Altuve has for the past two seasons. Duffy was productive in other ways, however, showing doubles power and a nice balance of patience and limited strikeouts.

Then 2015 rolled around, and the 24-year-old forced himself into an everyday role over Casey McGehee by hitting everything in sight. Duffy had eight homers in the first half of the season, performing 27 percent better than the average major-league hitter (while also barely showing his stolen-base ability). His average fly ball and home run distance currently sits at 297 feet, ranking 34th in the majors — just behind Andrew McCutchen. That power explosion, coupled with Duffy’s above average defensive work (something he was known for dating back to his college days), have put him in very good company among rookies in 2015. Here are the top 10 rookies in the first half of the season by Wins Above Replacement:


Chicago Cubs third baseman Kris Bryant, a second overall pick, ranks first. Dodgers center fielder Joc Pederson, who received the second-highest bonus out of all Dodgers draft picks in 2010, is second. Third is Duffy, who was taken in the 18th round and never homered in college. This is not to say that Duffy will continue to produce near the level of Bryant and Pederson, just that he has been in the conversation with these players for the first half of the season. Duffy has exceeded all expectations not just because he has excelled, but because there weren’t many expectations to begin with. Impressively, he’s done it much like Crawford and Panik have before him: through meaningful swing changes.

What changes did Duffy make to cause his breakout? There are a few notable differences in his swing from last season. First, a swing from late August of 2014:


And now a swing from just over a week ago:


Both of these pitches were fastballs resulting in doubles down the left-field line, and both were in traditional fastball counts. Comparing swings is often difficult, because it’s not known whether the specific swing featured exactly captures the larger picture. However, there are some major changes in these swings that can’t be ignored.

This season, his hands are lower and much quieter. He gets his front foot down a little quicker. His weight is more toward his back leg, with his lower body acting more explosively. Finally, he now finishes his swing high with his arms fully extended, only allowing one hand to remain on the bat. As a result, his whole upper body rotates more toward left field. Simply put, his swing is more explosive this year, and it’s resulting in a much higher percentage of hard-hit balls — especially to left field.

Given Duffy’s great batting eye in the minor leagues (he posted walk rates above 10 percent at three out of four levels), his current 4.4 percent walk rate has room to improve. With his great speed on the base paths, the steals he showcased in the minors may also come in time, and he’s going to get his share of infield hits.

In short, Duffy is a player with a history of patience and speed, and he has yet to really show those skills at the major-league level; his success this season has been built on an improved swing, a theme that’s becoming more and more common for Giants players under hitting coach Hensley Meulens. The continuing test for Duffy, of course, is pitchers adjusting to his success: he can certainly be expected to see less and less of the inside pitches he’s been feasting on in the first half of this season.

Duffy might not challenge Bryant and Pederson for Rookie of the Year honors, but the fact that he is in the conversation for best rookies in the first half of the season speaks volumes about the Giants’ development of position players. This year, they’ve turned two formerly light-hitting middle infielders into legitimate offensive threats, adding Duffy to the mix when he simply wouldn’t be denied. After checking all of the boxes for perhaps the best home-grown infield in the major leagues, the only question remaining is: who’s next in the Giants’ development queue?